Because the budget was so low, Ray Harryhausen saved money by building his octopus model with six rather than the correct eight tentacles. He tried to pose the creature so this lack of the right number of arms wasn't apparent.
The submarine scenes were shot in a real submarine in Long Beach, California.
City officials refused to allow the filmmakers to shoot on the real Golden Gate Bridge, because they didn't want the public to think that the bridge could fall. Ray Harryhausen recreated the entire bridge in miniature.
Kenneth Tobey completes a military trifecta in this movie. In The Thing from Another World (1951) he played an Air Force Captain, in The Beast from 20,000 Fathoms (1953) an Army Colonel and in this a Navy Commander.